US4274927A - Process for the electrolytic deposition of gold and gold alloy coatings and compositions therefore - Google Patents
Process for the electrolytic deposition of gold and gold alloy coatings and compositions therefore Download PDFInfo
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- US4274927A US4274927A US06/135,766 US13576680A US4274927A US 4274927 A US4274927 A US 4274927A US 13576680 A US13576680 A US 13576680A US 4274927 A US4274927 A US 4274927A
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- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical group [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 title claims abstract description 52
- 239000010931 gold Substances 0.000 title claims abstract description 51
- 229910052737 gold Inorganic materials 0.000 title claims abstract description 50
- 238000000576 coating method Methods 0.000 title claims abstract description 38
- 238000000034 method Methods 0.000 title claims abstract description 25
- 230000008021 deposition Effects 0.000 title claims abstract description 6
- 239000000203 mixture Substances 0.000 title claims description 34
- 229910001020 Au alloy Inorganic materials 0.000 title abstract description 15
- 239000003353 gold alloy Substances 0.000 title abstract description 15
- 150000003839 salts Chemical class 0.000 claims abstract description 26
- 239000003792 electrolyte Substances 0.000 claims abstract description 22
- ZMZDMBWJUHKJPS-UHFFFAOYSA-N hydrogen thiocyanate Natural products SC#N ZMZDMBWJUHKJPS-UHFFFAOYSA-N 0.000 claims abstract description 13
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 11
- 239000003513 alkali Substances 0.000 claims abstract description 7
- ZMZDMBWJUHKJPS-UHFFFAOYSA-M Thiocyanate anion Chemical compound [S-]C#N ZMZDMBWJUHKJPS-UHFFFAOYSA-M 0.000 claims abstract description 6
- XFXPMWWXUTWYJX-UHFFFAOYSA-N Cyanide Chemical compound N#[C-] XFXPMWWXUTWYJX-UHFFFAOYSA-N 0.000 claims abstract description 5
- 229910052802 copper Inorganic materials 0.000 claims abstract description 5
- 229910052763 palladium Inorganic materials 0.000 claims abstract description 5
- 229910052759 nickel Inorganic materials 0.000 claims abstract description 4
- 229910052718 tin Inorganic materials 0.000 claims abstract description 4
- 229910052793 cadmium Inorganic materials 0.000 claims abstract description 3
- 229910052707 ruthenium Inorganic materials 0.000 claims abstract description 3
- 229910052709 silver Inorganic materials 0.000 claims abstract description 3
- 229910052725 zinc Inorganic materials 0.000 claims abstract description 3
- 238000000151 deposition Methods 0.000 claims description 18
- 239000011248 coating agent Substances 0.000 claims description 17
- 229910045601 alloy Inorganic materials 0.000 claims description 16
- 239000000956 alloy Substances 0.000 claims description 16
- KDLHZDBZIXYQEI-UHFFFAOYSA-N Palladium Chemical compound [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 claims description 9
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims description 6
- ZNNZYHKDIALBAK-UHFFFAOYSA-M potassium thiocyanate Chemical compound [K+].[S-]C#N ZNNZYHKDIALBAK-UHFFFAOYSA-M 0.000 claims description 5
- VGTPCRGMBIAPIM-UHFFFAOYSA-M sodium thiocyanate Chemical compound [Na+].[S-]C#N VGTPCRGMBIAPIM-UHFFFAOYSA-M 0.000 claims description 5
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims description 4
- 239000010949 copper Substances 0.000 claims description 4
- 229910052751 metal Inorganic materials 0.000 claims description 4
- 239000002184 metal Substances 0.000 claims description 4
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 claims description 4
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 claims description 3
- 125000004093 cyano group Chemical group *C#N 0.000 claims description 3
- 229940116357 potassium thiocyanate Drugs 0.000 claims description 3
- SDKPSXWGRWWLKR-UHFFFAOYSA-M sodium;9,10-dioxoanthracene-1-sulfonate Chemical compound [Na+].O=C1C2=CC=CC=C2C(=O)C2=C1C=CC=C2S(=O)(=O)[O-] SDKPSXWGRWWLKR-UHFFFAOYSA-M 0.000 claims description 3
- KJTLSVCANCCWHF-UHFFFAOYSA-N Ruthenium Chemical compound [Ru] KJTLSVCANCCWHF-UHFFFAOYSA-N 0.000 claims description 2
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 claims description 2
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 claims description 2
- BDOSMKKIYDKNTQ-UHFFFAOYSA-N cadmium atom Chemical compound [Cd] BDOSMKKIYDKNTQ-UHFFFAOYSA-N 0.000 claims description 2
- FDWREHZXQUYJFJ-UHFFFAOYSA-M gold monochloride Chemical compound [Cl-].[Au+] FDWREHZXQUYJFJ-UHFFFAOYSA-M 0.000 claims description 2
- 229910052697 platinum Inorganic materials 0.000 claims description 2
- 239000004332 silver Substances 0.000 claims description 2
- 239000011701 zinc Substances 0.000 claims description 2
- 239000002585 base Substances 0.000 claims 14
- -1 alkali metal thiocyanate Chemical class 0.000 claims 8
- 229910052783 alkali metal Inorganic materials 0.000 claims 7
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 claims 1
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 claims 1
- 125000000858 thiocyanato group Chemical group *SC#N 0.000 claims 1
- 239000011135 tin Substances 0.000 claims 1
- 238000005275 alloying Methods 0.000 abstract description 3
- 239000000470 constituent Substances 0.000 abstract 1
- 150000002343 gold Chemical class 0.000 abstract 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 3
- DOBRDRYODQBAMW-UHFFFAOYSA-N copper(i) cyanide Chemical compound [Cu+].N#[C-] DOBRDRYODQBAMW-UHFFFAOYSA-N 0.000 description 3
- 238000005260 corrosion Methods 0.000 description 3
- 230000007797 corrosion Effects 0.000 description 3
- 150000002739 metals Chemical class 0.000 description 3
- NNFCIKHAZHQZJG-UHFFFAOYSA-N potassium cyanide Chemical compound [K+].N#[C-] NNFCIKHAZHQZJG-UHFFFAOYSA-N 0.000 description 3
- 239000010936 titanium Substances 0.000 description 3
- 229910052719 titanium Inorganic materials 0.000 description 3
- QCUOBSQYDGUHHT-UHFFFAOYSA-L cadmium sulfate Chemical compound [Cd+2].[O-]S([O-])(=O)=O QCUOBSQYDGUHHT-UHFFFAOYSA-L 0.000 description 2
- 229910000331 cadmium sulfate Inorganic materials 0.000 description 2
- 125000001309 chloro group Chemical class Cl* 0.000 description 2
- ORTQZVOHEJQUHG-UHFFFAOYSA-L copper(II) chloride Chemical compound Cl[Cu]Cl ORTQZVOHEJQUHG-UHFFFAOYSA-L 0.000 description 2
- 239000013078 crystal Substances 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 125000005402 stannate group Chemical group 0.000 description 2
- 238000005494 tarnishing Methods 0.000 description 2
- JIAARYAFYJHUJI-UHFFFAOYSA-L zinc dichloride Chemical compound [Cl-].[Cl-].[Zn+2] JIAARYAFYJHUJI-UHFFFAOYSA-L 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 229910021591 Copper(I) chloride Inorganic materials 0.000 description 1
- 229910021592 Copper(II) chloride Inorganic materials 0.000 description 1
- 229910000881 Cu alloy Inorganic materials 0.000 description 1
- 229910003771 Gold(I) chloride Inorganic materials 0.000 description 1
- 229910003767 Gold(III) bromide Inorganic materials 0.000 description 1
- 229910003803 Gold(III) chloride Inorganic materials 0.000 description 1
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 1
- WOFVPNPAVMKHCX-UHFFFAOYSA-N N#C[Au](C#N)C#N Chemical compound N#C[Au](C#N)C#N WOFVPNPAVMKHCX-UHFFFAOYSA-N 0.000 description 1
- 229910021586 Nickel(II) chloride Inorganic materials 0.000 description 1
- 229910021607 Silver chloride Inorganic materials 0.000 description 1
- 229910021626 Tin(II) chloride Inorganic materials 0.000 description 1
- 229910021627 Tin(IV) chloride Inorganic materials 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- NHMJUOSYSOOPDM-UHFFFAOYSA-N cadmium cyanide Chemical compound [Cd+2].N#[C-].N#[C-] NHMJUOSYSOOPDM-UHFFFAOYSA-N 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- KXZJHVJKXJLBKO-UHFFFAOYSA-N chembl1408157 Chemical compound N=1C2=CC=CC=C2C(C(=O)O)=CC=1C1=CC=C(O)C=C1 KXZJHVJKXJLBKO-UHFFFAOYSA-N 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- OXBLHERUFWYNTN-UHFFFAOYSA-M copper(I) chloride Chemical compound [Cu]Cl OXBLHERUFWYNTN-UHFFFAOYSA-M 0.000 description 1
- LEKPFOXEZRZPGW-UHFFFAOYSA-N copper;dicyanide Chemical compound [Cu+2].N#[C-].N#[C-] LEKPFOXEZRZPGW-UHFFFAOYSA-N 0.000 description 1
- OVWPJGBVJCTEBJ-UHFFFAOYSA-K gold tribromide Chemical compound Br[Au](Br)Br OVWPJGBVJCTEBJ-UHFFFAOYSA-K 0.000 description 1
- RJHLTVSLYWWTEF-UHFFFAOYSA-K gold trichloride Chemical compound Cl[Au](Cl)Cl RJHLTVSLYWWTEF-UHFFFAOYSA-K 0.000 description 1
- PMCMJPXEJUKOAO-UHFFFAOYSA-M gold(1+);bromide Chemical compound [Au]Br PMCMJPXEJUKOAO-UHFFFAOYSA-M 0.000 description 1
- IZLAVFWQHMDDGK-UHFFFAOYSA-N gold(1+);cyanide Chemical compound [Au+].N#[C-] IZLAVFWQHMDDGK-UHFFFAOYSA-N 0.000 description 1
- RQVOBHDSEHUCDG-UHFFFAOYSA-M gold(1+);thiocyanate Chemical compound [Au]SC#N RQVOBHDSEHUCDG-UHFFFAOYSA-M 0.000 description 1
- PDMYFWLNGXIKEP-UHFFFAOYSA-K gold(3+);trithiocyanate Chemical compound [Au+3].[S-]C#N.[S-]C#N.[S-]C#N PDMYFWLNGXIKEP-UHFFFAOYSA-K 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 239000000155 melt Substances 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- QMMRZOWCJAIUJA-UHFFFAOYSA-L nickel dichloride Chemical compound Cl[Ni]Cl QMMRZOWCJAIUJA-UHFFFAOYSA-L 0.000 description 1
- NLEUXPOVZGDKJI-UHFFFAOYSA-N nickel(2+);dicyanide Chemical compound [Ni+2].N#[C-].N#[C-] NLEUXPOVZGDKJI-UHFFFAOYSA-N 0.000 description 1
- PIBWKRNGBLPSSY-UHFFFAOYSA-L palladium(II) chloride Chemical compound Cl[Pd]Cl PIBWKRNGBLPSSY-UHFFFAOYSA-L 0.000 description 1
- CLSUSRZJUQMOHH-UHFFFAOYSA-L platinum dichloride Chemical compound Cl[Pt]Cl CLSUSRZJUQMOHH-UHFFFAOYSA-L 0.000 description 1
- INXLGDBFWGBBOC-UHFFFAOYSA-N platinum(2+);dicyanide Chemical compound [Pt+2].N#[C-].N#[C-] INXLGDBFWGBBOC-UHFFFAOYSA-N 0.000 description 1
- PQTLYDQECILMMB-UHFFFAOYSA-L platinum(2+);sulfate Chemical compound [Pt+2].[O-]S([O-])(=O)=O PQTLYDQECILMMB-UHFFFAOYSA-L 0.000 description 1
- PNKGEWJZNCQINU-UHFFFAOYSA-N ruthenium(3+);tricyanide Chemical compound [Ru+3].N#[C-].N#[C-].N#[C-] PNKGEWJZNCQINU-UHFFFAOYSA-N 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- LFAGQMCIGQNPJG-UHFFFAOYSA-N silver cyanide Chemical compound [Ag+].N#[C-] LFAGQMCIGQNPJG-UHFFFAOYSA-N 0.000 description 1
- 229940098221 silver cyanide Drugs 0.000 description 1
- HKZLPVFGJNLROG-UHFFFAOYSA-M silver monochloride Chemical compound [Cl-].[Ag+] HKZLPVFGJNLROG-UHFFFAOYSA-M 0.000 description 1
- 229910000367 silver sulfate Inorganic materials 0.000 description 1
- YPNVIBVEFVRZPJ-UHFFFAOYSA-L silver sulfate Chemical compound [Ag+].[Ag+].[O-]S([O-])(=O)=O YPNVIBVEFVRZPJ-UHFFFAOYSA-L 0.000 description 1
- RHUVFRWZKMEWNS-UHFFFAOYSA-M silver thiocyanate Chemical compound [Ag+].[S-]C#N RHUVFRWZKMEWNS-UHFFFAOYSA-M 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
- 239000011734 sodium Substances 0.000 description 1
- 229940071182 stannate Drugs 0.000 description 1
- 235000011150 stannous chloride Nutrition 0.000 description 1
- 150000003567 thiocyanates Chemical class 0.000 description 1
- AXZWODMDQAVCJE-UHFFFAOYSA-L tin(II) chloride (anhydrous) Chemical compound [Cl-].[Cl-].[Sn+2] AXZWODMDQAVCJE-UHFFFAOYSA-L 0.000 description 1
- HPGGPRDJHPYFRM-UHFFFAOYSA-J tin(iv) chloride Chemical compound Cl[Sn](Cl)(Cl)Cl HPGGPRDJHPYFRM-UHFFFAOYSA-J 0.000 description 1
- 235000005074 zinc chloride Nutrition 0.000 description 1
- 239000011592 zinc chloride Substances 0.000 description 1
- GTLDTDOJJJZVBW-UHFFFAOYSA-N zinc cyanide Chemical compound [Zn+2].N#[C-].N#[C-] GTLDTDOJJJZVBW-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D3/00—Electroplating: Baths therefor
- C25D3/02—Electroplating: Baths therefor from solutions
- C25D3/56—Electroplating: Baths therefor from solutions of alloys
- C25D3/62—Electroplating: Baths therefor from solutions of alloys containing more than 50% by weight of gold
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D3/00—Electroplating: Baths therefor
- C25D3/02—Electroplating: Baths therefor from solutions
- C25D3/48—Electroplating: Baths therefor from solutions of gold
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D3/00—Electroplating: Baths therefor
- C25D3/66—Electroplating: Baths therefor from melts
Definitions
- the invention is directed to a composition and process for the electrolytic deposition of gold and gold alloy coatings out of an electrolyte that contains or consists of a salt melt.
- Gold and gold alloy coatings are in use in many areas of the art in order to enable objects or to protect them from the influence of corrosion.
- Gold and gold alloy coatings are used especially for electrical contacts in the low-voltage current art and in the semi-conductor industry.
- high carat gold coatings guarantee a sufficient resistance to tarnish and therewih a constant low electric resistance of the contacts to the passage of current.
- an electrolyte which comprises or consists of a salt melt which contains a gold salt, alkali thiocyanate and in a given case a salt of one or more alloying metals.
- the electrolyte contains 0.5-20 grams of gold per liter of salt melt in the form of a thiocyanate, cyano and/or chloro compounds of mono or trivalent gold, e.g. gold (I) chloride, gold (III) chloride, gold (I) cyanide, gold (III) cyanide, gold (I) bromide, gold (III) bromide, gold (I) thiocyanate and gold (III) thiocyanate.
- gold (I) chloride, gold (III) chloride, gold (I) cyanide, gold (III) cyanide, gold (I) bromide, gold (III) bromide, gold (I) thiocyanate and gold (III) thiocyanate Particularly proven good are baths containing 5 to 15 grams of gold per liter of salt melt.
- alkali thiocyanate there is advantageously used a mixture of 70 mol % potassium thiocyanate and 30 mol % sodium thiocyanate having a melting point of about 125° C.
- alkali thiocyanate there is advantageously used a mixture of 70 mol % potassium thiocyanate and 30 mol % sodium thiocyanate having a melting point of about 125° C.
- sodium thiocyanate or potassium thiocyanate individually.
- alkali cyanide e.g. sodium cyanide or potassium cyanide
- alkali cyanide e.g. sodium cyanide or potassium cyanide
- water e.g. water
- alloying metals there are usuable silver, palladium, ruthenium, platinum as well as copper, zinc, cadmium, nickel and tin in amounts up to 300 grams, particularly in amounts of 5 to 280 grams per liter of salt melt in the form of a salt soluble in the melt.
- Particularly recommended are the thiocyanate, chloro, sulfato and/or cyano compounds of these metals, e.g.
- Tin is preferably added as the hexahydroxy stannates, e.g. sodium hexahydroxy stannate.
- the deposition takes place preferably at temperatures of 100° to 200° C., especially at 150° C.
- insoluble anodes e.g. carbon or platimited titanium.
- low carat gold coatings i.e. below 20 carats
- e.g. 18 or 16 (or even 14) carat which are equal to pure gold or high carat gold alloy coatings in their tarnish and corrosion resistance.
- X-ray examinations on the thus produced gold alloy coatings show that the structure is substantially homogeneous and a mixed crystal formation has occurred.
- Corrosion tests as well as measurements of electric current resistance prove that these low carat gold alloy coatings have a high tarnish resistance.
- compositions can comprise, consist essentially of or consist of the material set forth and the process can comprise, consist essentially of or consist of the steps set forth with said materials.
- German priority application P 29 14 879.6 is hereby incorporated by reference.
- insoluble anode platimited titanium is used as insoluble anode platimited titanium.
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Electroplating And Plating Baths Therefor (AREA)
- Electroplating Methods And Accessories (AREA)
Abstract
For the electrolytic deposition of gold alloys there is required a process with which low carat coatings can be deposited which nevertheless have a high resistance to tarnish. Such coatings are obtained from electrolytes which consist of a salt melt and contain gold salts, alkali thiocyanate and salts of one or more alloyings elements as constituents. Preferably the electrolyte contains per liter of salt melt 0.5 to 20 grams of gold, up to 300 grams of Cu, Zn, Sn, Cd, Ni, Ag, Pd, Ru and/or Pt, up to 200 grams of alkali cyanide and/or water.
Description
The invention is directed to a composition and process for the electrolytic deposition of gold and gold alloy coatings out of an electrolyte that contains or consists of a salt melt.
Gold and gold alloy coatings are in use in many areas of the art in order to enable objects or to protect them from the influence of corrosion. Gold and gold alloy coatings are used especially for electrical contacts in the low-voltage current art and in the semi-conductor industry. In the previously customary wet galvanic process indeed only high carat gold coatings guarantee a sufficient resistance to tarnish and therewih a constant low electric resistance of the contacts to the passage of current.
Because of the high price of gold, for industrial uses for reasons of economy it would be desirable to employ low carat gold alloy coatings which would have to be the equal of the high carat coatings in regard to their resistance to tarnish.
Such wet galvanic depositing low carat gold alloy coatings (<20 carats) however, are for the most part not equal to the high requirements in industrial use. The reasons for the lack of tarnish resistance of these coatings probably is due to the fact that the deposits are heterogeneous and under these conditions of operation there are only partially built mixed crystals from the alloy components, which alone would guarantee a sufficient resistance to tarnishing.
Therefore it was the problem of the present invention to develop a process for the electrolytic deposition of gold and gold alloy coatings with which low carat gold coatings also permit the production of low carat gold coatings having higher resistance to tarnishing in air or other medium.
This problem was solved according to the invention by providing an electrolyte which comprises or consists of a salt melt which contains a gold salt, alkali thiocyanate and in a given case a salt of one or more alloying metals.
Preferably the electrolyte contains 0.5-20 grams of gold per liter of salt melt in the form of a thiocyanate, cyano and/or chloro compounds of mono or trivalent gold, e.g. gold (I) chloride, gold (III) chloride, gold (I) cyanide, gold (III) cyanide, gold (I) bromide, gold (III) bromide, gold (I) thiocyanate and gold (III) thiocyanate. Particularly proven good are baths containing 5 to 15 grams of gold per liter of salt melt.
As alkali thiocyanate there is advantageously used a mixture of 70 mol % potassium thiocyanate and 30 mol % sodium thiocyanate having a melting point of about 125° C. However, there can also be used other mixture ratios and other thiocyanate components for the process of the invention. There can also be used sodium thiocyanate or potassium thiocyanate individually.
It has proven especially advantageous if there is added to the electrolyte up to 200 grams of alkali cyanide, e.g. sodium cyanide or potassium cyanide, per liter or salt melt and/or up to 200 ml of water per liter of salt melt. Thus when alkali cyanide is present it is usually present in an amount of at least 20 grams per liter of salt melt. Likewise when water is present, it is usually present in an amount of at least 20 grams per liter of salt melt.
As alloying metals there are usuable silver, palladium, ruthenium, platinum as well as copper, zinc, cadmium, nickel and tin in amounts up to 300 grams, particularly in amounts of 5 to 280 grams per liter of salt melt in the form of a salt soluble in the melt. Particularly recommended are the thiocyanate, chloro, sulfato and/or cyano compounds of these metals, e.g. compounds such as silver cyanide, silver thiocyanate, silver chloride or silver sulfate, palladium chloride, palladium cyanide, ruthenium cyanide, platinum (II) cyanide, platinum (II) sulfate, Platinum (II) chloride, copper (I) cyanide, copper (II) cyanide, copper (I) chloride, copper (II) chloride, zinc chloride, zinc cyanide, cadmium sulfate, nickel (II) chloride, nickel cyanide, cadmium cyanide, cadmium sulfate, tin (II) chloride, tin (IV) chloride. Tin is preferably added as the hexahydroxy stannates, e.g. sodium hexahydroxy stannate.
The deposition takes place preferably at temperatures of 100° to 200° C., especially at 150° C. Advantageously there are employed hereby insoluble anodes e.g. carbon or platimited titanium.
With the process of the invention there can be deposited low carat gold coatings (i.e. below 20 carats) of e.g. 18 or 16 (or even 14) carat which are equal to pure gold or high carat gold alloy coatings in their tarnish and corrosion resistance. X-ray examinations on the thus produced gold alloy coatings show that the structure is substantially homogeneous and a mixed crystal formation has occurred. Corrosion tests as well as measurements of electric current resistance prove that these low carat gold alloy coatings have a high tarnish resistance.
Besides low carat gold alloy coating naturally there can also be deposited according to the process of the invention pure gold and high carat gold coatings.
Unless otherwise indicated all parts and percentages are by weight.
The compositions can comprise, consist essentially of or consist of the material set forth and the process can comprise, consist essentially of or consist of the steps set forth with said materials.
The following examples further describe the process of the invention.
1 kg of a mixture of KSCN and NaSCN (70:30 mole %) was melted and brought to a temperature of 150° C. Subsequently there were added 100 ml of water, 100 grams of KCN, 50 grams of copper as copper (I) cyanide and 5 grams of gold as K[Au(CN)2 ]. At a current density of 0.6 A/dm2 there deposited on a nickel under layer an 18 carat gold-copper-alloy coating which was distinguished by a high tarnish resistance. By variations of the current density as is known in the art the carat content of the coatings can be changed. As an insoluble anode platimated titanium is used.
There were added to 1 kg of a mixture of KSCN and NaSCN according to Example 1 (70:30 mole %) 80 ml of water, 100 grams of KCN, 4 grams of gold as KAu(CN)2, 50 grams of copper as copper (I) cyanide 60 grams of palladium as K2 Pd(CN)4. At a temperature of 160° C. and a current density of 0.3 A/dm2 there was obtained an 18 carat gold alloy coating and at a current density of 0.6 A/dm2 there was obtained a 16 carat coating. Both coatings showed a high resistance to stain.
The entire disclosure of German priority application P 29 14 879.6 is hereby incorporated by reference. As insoluble anode platimited titanium is used.
Claims (24)
1. A composition suitable for the electrolytic deposition of gold or a gold base alloy comprising an electrolyte which is a salt melt bath and consists essentially of a gold salt and an alkali metal thiocyanate or a mixture of a gold salt, alkali metal thiocyanate and a salt of at least one metal forming an alloy with gold and which salt melt bath contains water in an amount of 20 to 200 ml per liter of melt.
2. A composition according to claim 1 wherein the electrolyte contain 0.5 to 20 grams of gold per liter of salt melt, the gold being present as mono or trivalent gold as a thiocyanato, cyano or chloro gold compound or as a mixture thereof.
3. A composition according to claim 2 wherein the electrolyte contains 5-15 grams of gold per liter of salt melt.
4. A composition according to claim 2 wherein the alkali metal thiocyanate is present as a mixture of 70 mole % potassium thiocyanate and 30 mole % of sodium thiocyanate.
5. A composition according to claim 2 wherein alkali metal cyanide is also present and is present in an amount up to 200 grams of alkali cyanide per liter of melt.
6. A composition according to claim 5 wherein the water is present in an amount of 80 to 100 ml of water per kilogram of alkali metal thiocyanate.
7. A composition according to claim 2 wherein the water is present in an amount of 80 to 100 ml of water per kilogram of alkali metal thiocyanate.
8. A composition according to claim 2 wherein there is present in the salt melt a soluble salt of copper, zinc, cadmium, nickel, tin, silver, palladium, ruthenium or platinum, said soluble salt being present in an amount of up to 300 grams per liter of salt melt.
9. A composition according to claim 8 wherein the water is present in an amount of 80 to 100 ml per kilogram of alkali metal thiocyanate.
10. A composition according to claim 8 wherein the soluble salt is present in an amount of 5 to 280 grams per liter salt melt.
11. A composition according to claim 10 wherein the soluble salt is a thiocyanate, chloride, sulfate or cyano compound.
12. In a process of electrolytically depositing gold or a gold base alloy coating the improvement comprising employing as the electrolyte the composition of claim 1.
13. In a process of electrolytically depositing gold or a gold base alloy coating the improvement comprising employing as the electrolyte the composition of claim 2.
14. In a process of electrolytically depositing gold or a gold base alloy coating the improvement comprising employing as the electrolyte the composition of claim 3.
15. In a process of electrolytically depositing gold or a gold base alloy coating the improvement comprising employing as the electrolyte the composition of claim 4.
16. In a process of electrolytically depositing gold or a gold base alloy coating the improvement comprising employing as the electrolyte the composition of claim 5.
17. In a process of electrolytically depositing gold or a gold base alloy coating, the improvement comprising employing as the electrolyte the composition of claim 6.
18. In a process of electrolytically depositing gold or a gold base alloy coating, the improvement comprising employing as the electrolyte the composition of claim 7.
19. In a process of electrolytically depositing gold or a gold base alloy coating, the improvement comprising employing as the electrolyte the composition of claim 8.
20. In a process of electrolytically depositing a gold or a gold base alloy coating, the improvement comprising employing as the electrolyte the composition of claim 9.
21. In a process of electrolytically depositing gold or a gold base alloy coating, the improvement comprising employing as the electrolyte the composition of claim 10.
22. In a process of electrolytically depositing gold or a gold base alloy coating, the improvement comprising employing as the electrolyte the composition of claim 11.
23. In a process of electrolytically depositing gold or a gold base alloy coating, the improvement comprising employing as the electrolyte the composition of claim 11 and the process is carried out at 100° to 200° C.
24. In a process of electrolytically depositing a gold or gold base alloy coating, the improvement comprising employing as the electrolyte the composition of claim 2 and the process is carried out at 100° to 200° C.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE2914879 | 1979-04-12 | ||
| DE19792914879 DE2914879A1 (en) | 1979-04-12 | 1979-04-12 | METHOD FOR ELECTROLYTICALLY DEPOSITING GOLD AND GOLD ALLOY LAYERS |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| US4274927A true US4274927A (en) | 1981-06-23 |
Family
ID=6068179
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| US06/135,766 Expired - Lifetime US4274927A (en) | 1979-04-12 | 1980-03-31 | Process for the electrolytic deposition of gold and gold alloy coatings and compositions therefore |
Country Status (5)
| Country | Link |
|---|---|
| US (1) | US4274927A (en) |
| JP (1) | JPS55148795A (en) |
| DE (1) | DE2914879A1 (en) |
| FR (1) | FR2453914A1 (en) |
| GB (1) | GB2047276B (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2771219A (en) * | 1954-12-28 | 1956-11-20 | Roberta L Dewey | Integrated holder and dispenser |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4149942A (en) * | 1974-04-10 | 1979-04-17 | Stutterheim F Von | Process for dissolving metals in fused salt baths |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE2417424C3 (en) * | 1974-04-10 | 1981-10-15 | Friedrich von Dipl.-Phys. Dr. 6370 Oberursel Stutterheim | Process for dissolving metals in molten salt and using the resulting solutions |
-
1979
- 1979-04-12 DE DE19792914879 patent/DE2914879A1/en not_active Withdrawn
-
1980
- 1980-03-31 US US06/135,766 patent/US4274927A/en not_active Expired - Lifetime
- 1980-04-08 GB GB8011544A patent/GB2047276B/en not_active Expired
- 1980-04-10 JP JP4629780A patent/JPS55148795A/en active Pending
- 1980-04-11 FR FR8008208A patent/FR2453914A1/en active Granted
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4149942A (en) * | 1974-04-10 | 1979-04-17 | Stutterheim F Von | Process for dissolving metals in fused salt baths |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2771219A (en) * | 1954-12-28 | 1956-11-20 | Roberta L Dewey | Integrated holder and dispenser |
Also Published As
| Publication number | Publication date |
|---|---|
| DE2914879A1 (en) | 1980-10-23 |
| GB2047276B (en) | 1983-04-20 |
| FR2453914B1 (en) | 1984-01-27 |
| GB2047276A (en) | 1980-11-26 |
| FR2453914A1 (en) | 1980-11-07 |
| JPS55148795A (en) | 1980-11-19 |
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